Tech

As the foremost economic zone in China, the Yangtze River Delta (YRD) region has recently been experiencing more frequent haze events, resulting in dramatic damages to human and ecosystem health.

Anthropogenic aerosol emissions play a key role in affecting the formation of haze events. However, aside from local sources of pollution, some studies have found that external and preceding climate drivers, such as Arctic sea ice and subtropical western Pacific sea surface temperature, are also influential factors. However, most research has mainly been confined to analyzing the effects on haze pollution in the Northern Hemisphere, with few considering the Southern Hemisphere.

"We found that the December sea surface temperature in the tropical Indian Ocean has a significant positive correlation with the number of haze days in January over the Yangtze River Delta region, especially during 1999-2017," says Dr. YIN Zhicong, a Professor at Nanjing University of Information Science & Technology and corresponding author of a paper recently published in Atmospheric and Oceanic Science Letters.

YIN and his team used observational analyses and numerical experiments to investigate the meteorological conditions associated with haze pollution, with the main emphasis placed upon the impacts of the preceding sea surface temperature in the tropical Indian Ocean.

The results indicated that a positive sea surface temperature in the tropical Indian Ocean will provoke a series of Rossby wave trains in the upper troposphere, transmitting signals from the tropics to East Asia. Near the surface, favorable local meteorological conditions such as increased surface air temperature, southerly winds, reduced surface wind speed, and influences from upstream areas, are conducive to the occurrence of haze. These observational results were also reproduced well in model simulations.

"The findings of this research will help us to better understand the remote influences of sea surface temperature in the tropical Indian Ocean on haze pollution and provide a potentially new bridge connecting the Northern and Southern Hemispheres and transmission signals. However, in the future, further studies are still needed for us to fully understand the tropical Indian Ocean," YIN concludes.

Researchers have answered key questions to help prevent damage and improve the safety of hydraulic systems used for pipelines, water turbines and other applications.

The work, led by engineers at the University of Waterloo, investigates a phenomenon known as cavitation, or the formation and collapse of destructive gas-filled bubbles resulting from rapid pressure changes in liquids.

Cavitation is behind a well-known party trick that involves shattering the bottom of a liquid-filled bottle by striking its open top with the palm of your hand.

"The growth and collapse of cavitation bubbles are fascinating," said  Zhao Pan, a professor of mechanical and mechatronics engineering who led the research. "They are usually small and fast, but they can cause serious damage even on surfaces such as hard alloys and glass."

The researchers developed a theoretical model to predict the formation and size of large, particularly damaging bubbles based on the acceleration and velocity of fluid flow. Experiments using high-speed photography validated the theory.

Information provided by the model will help engineers design hydraulic systems and develop operation guidelines to minimize wear and tear, avoid major failures, and improve the reliability of the technology.

In the party trick, hitting the bottle causes high acceleration of the liquid relative to the walls of the bottle. That reduces the pressure of the liquid at the bottom, triggering the rapid formation of gaseous bubbles.

When those bubbles collapse, or implode, they temporarily create high temperatures, high-speed micro-jets and shockwaves. Those effects are powerful enough to break the glass.

The phenomenon is a common culprit in damaged water pipes and ship propellers, for example. In extreme cases, it has led to disastrous pipe failures in hydropower plants.

"On the other hand, the power of these bubbles can also be harnessed for good," Pan said. "Cavitation can be used to break up kidney stones, kill bacteria without using chemicals, and even in the production of beer and chocolate."

Pan previously worked with researchers in Japan and the United States on a new theory of small cavitation bubbles caused by the acceleration of liquids that explained how the trick works. Recent work extends those results to the prediction of large bubbles. A paper on the research, On the criteria of large cavitation bubbles in a tube during a transient process, appears in the Journal of Fluid Mechanics. Pan collaborated on the new study with researchers from Tsinghua University in China.

In the 1930s, English climatologist, Sir Gilbert Walker, successfully predicted Indian summer monsoon rainfall (ISMR) based on the relationship between Southern Oscillation and ISMR connected by what is later-called Walker circulation, which is regarded as the first achievement of modern climate prediction with a clear physical mechanism. The Southern Oscillation was also recognized as the atmospheric component of El Nino-Southern Oscillation (ENSO).

However, at the end of the 20th century, a research in Science led by Indian climatologist Krishna Kumar found the significant reverse relationship between ENSO and Indian rainfall has been weakening since the 1970s, impairing the predictability of ISMR. Since then, the instability of the ENSO-Indian rainfall relationship has been an extremely hot topic in climatology research, but its mechanism remains puzzling.

Recently, a study published in The Innovation, led by Prof. Ping Huang from Institute of Atmospheric Physics at the Chinese Academy of Sciences, found that the ENSO-Indian rainfall relationship has been restoring since 1999/2000, confirmed by multiple dataset sources.

This study first identified that the diversity of ENSO's evolution, continuing from the previous winter or emerging from late spring, is the dominant factor perturbing the ENSO-ISMR relationship, with tropical Atlantic SST anomalies as the crucial bridge. During 1979-1997, ENSO events in summer mainly continued from the previous winter, which can drive apparent Atlantic Niña SST anomalies to offset ENSO's impact on ISMR and weaken the ENSO-ISMR relationship. In contrast, when ENSO events newly emerge from late spring, as they have done more recently during 2000-2018, the associated tropical Atlantic SST anomalies are weak and shift to the tropical North Atlantic, which can induce easterly anomalies to suppress ISMR and reinforce the ENSO-ISMR relationship.

"We believe this result can promote the study on ISMR prediction, ENSO's diversity and the inter-basin interaction." said Prof. Huang. "The clarification on the ENSO-ISMR relationship can also restore our confidence in the climate prediction based on physical process when the application of machine learning method is rapidly developing."

Ammonia (NH3) is among the most important chemicals produced by humans and has a promising future in sustainable energy applications besides being used in fertilizer production. Unfortunately, so far, the only realistic way that exists to produce ammonia at an industrial scale is through the Haber-Bosch process. This technique, discovered in the 19th century, is very energy-intensive and environmentally unfriendly; about 2% of the yearly global CO2 emissions come from Haber-Bosch processes.

"Considering the threats posed by global warming, it is high time we swap to an ammonia synthesis route with zero CO2 emissions," says Professor Sangaraju Shanmugam from Daegu Gyeongbuk Institute of Science and Technology (DGIST), Korea. Shanmugam and colleagues at DGIST have been working on finding new ways to produce ammonia through electrochemical reactions at room temperature using the nitrogen (N2) naturally present in air, a process technically known as 'electrocatalytic fixation of atmospheric N2.'

Although various research groups have successfully developed catalysts for electrochemical cells with high ammonia production rates, many suffer from low efficiency and selectivity towards N2. Others require precious metals or complex synthesis processes, which limits their applicability on an industrial scale. In a recent study published in Applied Catalysis B: Environmental, DGIST scientists led by Prof. Shanmugam tackled all these issues with a novel catalyst for electrochemical ammonia synthesis.

Their approach is based on molybdenum nitride (Mo2N) nanoparticles, which share electrical properties with the enzyme nitrogenase that some bacteria use to produce ammonia in nature. Nanoparticles alone don't make the cut; however, because they tend to stick to each other, this agglomeration reduces the total surface area that is exposed to N2 and thus hinders the catalyst's performance. To combat this problem, the scientists produced two-dimensional hexagonal boron nitride (h-BN) sheets and tailored them to contain defects. These defects--boron and nitrogen vacancies--provided sites for the Mo2N nanoparticles to anchor themselves without agglomerating much.

With this catalyst, the team managed to synthesize ammonia at a high rate with an efficiency of 61.5% in a stable and robust way. Most notably, the entire fabrication process of the low-cost ?-Mo2N/h-BN catalyst can be done in a single step, which makes it an attractive option in terms of industrial scalability. Furthermore, the study provided important insight into how the size of the nanoparticles affects the selectivity of the catalyst for nitrogen fixation. Prof. Shanmugam observes: "We believe our work will greatly contribute to the development of efficient catalysts. Advancing alternative technologies for the production of valuable chemicals like ammonia via electrocatalytic methods shall pave the way for a cleaner and safer environment."

Hopefully, further studies will finally allow us to abandon the methods of yesterday in favor of the sustainable alternatives of tomorrow.

Researchers at the University of British Columbia have discovered three liquid phases in aerosol particles, changing our understanding of air pollutants in the Earth's atmosphere.

While aerosol particles were known to contain up to two liquid phases, the discovery of an additional liquid phase may be important to providing more accurate atmospheric models and climate predictions. The study was published today in PNAS.

"We've shown that certain types of aerosol particles in the atmosphere, including ones that are likely abundant in cities, can often have three distinct liquid phases." says Dr. Allan Bertram, a professor in the department of chemistry. "These properties play a role in air quality and climate. What we hope is that these results improve models used in air quality and climate change policies."

Aerosol particles fill the atmosphere and play a critical role in air quality. These particles contribute to poor air quality and absorb and reflect solar radiation, affecting the climate system. Nevertheless, how these particles behave remains uncertain. Prior to 2012, it was often assumed in models that aerosol particles contained only one liquid phase.

In 2012, researchers from the University of British Columbia and Harvard University provided the first observations of two liquid phases in particles collected from the atmosphere. More recently, researchers at UBC hypothesized three liquid phases could form in atmospheric particles if the particles consisted of low polarity material, medium polarity material, and salty water.

To test this, a solvatochromic dye--a dye that changes color depending on polarity of its surroundings--was injected into particles containing a mixture of all three of these components. Although the solvatochromic dye method has been used widely in biology and chemistry, it has not been used to characterize the phase behaviour of atmospheric aerosols. Remarkably, three different colors were observed in these particles, confirming the presence of three liquid phases.

Scientists were also able to study the properties of particles containing three phases, including how well these particles acted as seeds for clouds, and how fast gases go into and out of the particles.

The study focused on particles containing mixtures of lubricating oil from gas vehicles, oxidized organic material from fossil fuel combustion and trees, and inorganic material from fossil fuel combustion. Depending on the properties of the lubricating oil and the oxidized organic material, different number of liquid phases will appear resulting in different impacts on air quality and climate.

"Through what we've shown, we've improved our understanding of atmospheric aerosols. That should lead to better predictions of air quality and climate, and better prediction of what is going to happen in the next 50 years," says Dr. Bertram. "If policies are made based on a model that has high uncertainties, then the policies will have high uncertainties. I hope we can improve that."

With the urgency of climate goals, policy that is built on accurate atmospheric modelling reduces the possibility of using resources and finances toward the wrong policies and goals.

RICHMOND, Va. (April 12, 2021) -- E-cigarettes that deliver a cigarette-like amount of nicotine are associated with reduced smoking and reduced exposure to the major tobacco-related pulmonary carcinogen, NNAL, even with concurrent smoking, according to a new study led by researchers at Virginia Commonwealth University and Penn State College of Medicine in Hershey, Pennsylvania.

The study, which will be published in The Lancet Respiratory Medicine journal, provides new and important information for smokers who may be trying to use e-cigarettes as a means to cut down on their smoking habit and lower their exposure to harmful toxicants.

"[We found] e-cigarettes with nicotine delivery like a combustible cigarette were effective in helping reduce smoking and exposure to a tobacco-related carcinogen," said lead author Caroline O. Cobb, Ph.D., an associate professor in the VCU Department of Psychology in the College of Humanities and Sciences. "But it doesn't just happen by accident. It requires the smoker to be actively trying to reduce their smoking by replacing it with e-cigarette use."

The researchers conducted a randomized controlled trial of 520 participants who smoked more than nine cigarettes a day, were not currently using an e-cigarette device, and were interested in reducing smoking but not quitting.

Over 24 weeks, participants used an e-cigarette device filled with either 0, 8 or 36 milligrams per milliliter of liquid nicotine or a plastic tube (shaped like a cigarette) that delivered no nicotine or aerosol. The e-cigarette conditions were chosen to reflect a range of nicotine delivery, either none, low (8 mg/ml) or cigarette-like (36 mg/ml). The participants were also provided with smoking reduction instructions.

At weeks 0, 4, 12 and 24, the researchers sampled participants' urine, testing for the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol, also known as NNAL. They found that participants using e-cigarettes filled with the cigarette-like level of liquid nicotine had significantly lower levels of NNAL at week 24 compared to baseline and compared to levels observed in the non-e-cigarette control condition.

The findings represent an important addition to the scientific literature because it suggests that when e-cigarettes deliver nicotine effectively, smokers have greater success in reducing their smoking and tobacco-related toxicant exposure. This study is important for two reasons, Cobb said.

"First, many e-cigarettes have poor nicotine delivery profiles, and our results suggest that those products may be less effective in helping smokers change their behavior and associated toxicant exposure," she said.

"Second, previous randomized controlled trials examining if e-cigarettes help smokers change their smoking behavior/toxicant exposure have used e-cigarettes with low or unknown nicotine delivery profiles," she said. "Our study highlights the importance of characterizing the e-cigarette nicotine delivery profile before conducting a randomized controlled trial. This work also has other important strengths over previous studies including the sample size, length of intervention, multiple toxicant exposure measures and control conditions."

The question of whether an e-cigarette's nicotine delivery profile is predictive of its ability to reduce harm and promote behavior change among smokers remains highly relevant to policymakers, public health advocates, health care providers and smoking populations. That knowledge will lead to better designed studies of the potential harms and benefits of e-cigarettes and ultimately inform tobacco regulatory policy, Cobb said.

The study contributes to the ongoing question of what role e-cigarettes play in changing smoking behavior.

Jonathan Foulds, Ph.D., professor of public health sciences at Penn State (one of the two study sites), commented, "This study shows that when smokers interested in reduction are provided with an e-cigarette with cigarette-like nicotine delivery, they are more likely to achieve significant decreases in tobacco-related toxicants, such as lower exhaled carbon monoxide levels."

Additionally, the study's findings support limited safety concerns for the use of the specific e-cigarette/liquid combinations over the short term, even in the context of concurrent cigarette smoking. However, Cobb added, very little is known about the effects of e-cigarettes over the course of years, as opposed to the study's 24-week period.

KEY POINTS:

- Loss of pleasure has been revealed as a key feature in early-onset dementia (FTD), in contrast to Alzheimer's disease.

- Scans showed grey matter deterioration in the so-called pleasure system of the brain.

- These regions were distinct from those implicated in depression or apathy - suggesting a possible treatment target.

People with early-onset dementia are often mistaken for having depression and now Australian research has discovered the cause: a profound loss of ability to experience pleasure - for example a delicious meal or beautiful sunset - related to degeneration of 'hedonic hotspots' in the brain where pleasure mechanisms are concentrated.

The University of Sydney-led research revealed marked degeneration, or atrophy, in frontal and striatal areas of the brain related to diminished reward-seeking, in patients with frontotemporal dementia (FTD).

The researchers believe it is the first study to demonstrate profound anhedonia - the clinical definition for a loss of ability to experience pleasure - in people with FTD.

Anhedonia is also common in people with depression, bipolar disorder and obsessive-compulsive disorder and can be particularly disabling for the individual.

In the study, patients with FTD - which generally affects people aged 40-65 - displayed a dramatic decline from pre-disease onset, in contrast to patients with Alzheimer's disease, who were not found to show clinically significant anhedonia.

The results point to the importance of considering anhedonia as a primary presenting feature of FTD, where researchers found neural drivers in areas that are distinct from apathy or depression.

The findings were published today in the leading neuroscience journal, Brain.

The paper's senior author, Professor Muireann Irish from the University of Sydney's Brain and Mind Centre and School of Psychology in the Faculty of Science, said despite increasing evidence of motivational disturbances, no study had previously explored the capacity to experience pleasure in people with FTD.

"Much of human experience is motivated by the drive to experience pleasure but we often take this capacity for granted.

"But consider what it might be like to lose the capacity to enjoy the simple pleasures of life - this has stark implications for the wellbeing of people affected by these neurodegenerative disorders.

"Our findings also reflect the workings of a complex network of regions in the brain, signaling potential treatments," said Professor Irish, who also recently published a paper in Brain about moral reasoning in FTD.

"Future studies will be essential to address the impact of anhedonia on everyday activities, and to inform the development of targeted interventions to improve quality of life in patients and their families."

New research shows that people who experience big dips in blood sugar levels, several hours after eating, end up feeling hungrier and consuming hundreds more calories during the day than others.

A study published today in Nature Metabolism, from PREDICT, the largest ongoing nutritional research program in the world that looks at responses to food in real life settings, the research team from King's College London and health science company ZOE (including scientists from Harvard Medical School, Harvard T.H. Chan School of Public Health, Massachusetts General Hospital, the University of Nottingham, Leeds University, and Lund University in Sweden) found why some people struggle to lose weight, even on calorie-controlled diets, and highlight the importance of understanding personal metabolism when it comes to diet and health.

The research team collected detailed data about blood sugar responses and other markers of health from 1,070 people after eating standardized breakfasts and freely chosen meals over a two-week period, adding up to more than 8,000 breakfasts and 70,000 meals in total. The standard breakfasts were based on muffins containing the same amount of calories but varying in composition in terms of carbohydrates, protein, fat and fibre. Participants also carried out a fasting blood sugar response test (oral glucose tolerance test), to measure how well their body processes sugar.

Participants wore stick-on continuous glucose monitors (CGMs) to measure their blood sugar levels over the entire duration of the study, as well as a wearable device to monitor activity and sleep. They also recorded levels of hunger and alertness using a phone app, along with exactly when and what they ate over the day.

Previous studies looking at blood sugar after eating have focused on the way that levels rise and fall in the first two hours after a meal, known as a blood sugar peak. However, after analyzing the data, the PREDICT team noticed that some people experienced significant 'sugar dips' 2-4 hours after this initial peak, where their blood sugar levels fell rapidly below baseline before coming back up.

Big dippers had a 9% increase in hunger, and waited around half an hour less, on average, before their next meal than little dippers, even though they ate exactly the same meals.

Big dippers also ate 75 more calories in the 3-4 hours after breakfast and around 312 calories more over the whole day than little dippers. This kind of pattern could potentially turn into 20 pounds of weight gain over a year.

Dr Sarah Berry from King's College London said, "It has long been suspected that blood sugar levels play an important role in controlling hunger, but the results from previous studies have been inconclusive. We've now shown that sugar dips are a better predictor of hunger and subsequent calorie intake than the initial blood sugar peak response after eating, changing how we think about the relationship between blood sugar levels and the food we eat."

Professor Ana Valdes from the School of Medicine at the University of Nottingham, who led the study team, said: "Many people struggle to lose weight and keep it off, and just a few hundred extra calories every day can add up to several pounds of weight gain over a year. Our discovery that the size of sugar dips after eating has such a big impact on hunger and appetite has great potential for helping people understand and control their weight and long-term health."

Comparing what happens when participants eat the same test meals revealed large variations in blood sugar responses between people. The researchers also found no correlation between age, bodyweight or BMI and being a big or little dipper, although males had slightly larger dips than females on average.

There was also some variability in the size of the dips experienced by each person in response to eating the same meals on different days, suggesting that whether you're a dipper or not depends on individual differences in metabolism, as well as the day-to-day effects of meal choices and activity levels.

Choosing foods that work together with your unique biology could help people feel fuller for longer and eat less overall.

Lead author on the study, Patrick Wyatt from ZOE, notes, "This study shows how wearable technology can provide valuable insights to help people understand their unique biology and take control of their nutrition and health. By demonstrating the importance of sugar dips, our study paves the way for data-driven, personalized guidance for those seeking to manage their hunger and calorie intake in a way that works with rather than against their body."

Tim Spector, Professor of Genetic Epidemiology at King's College London and scientific co-founder of ZOE, concludes, "Food is complex and humans are complicated, but our research is finally starting to open up the black box between diet and health. We're excited to have been able to turn this cutting-edge science into an at-home nutrition and microbiome test so that everyone has the opportunity to discover their unique responses to food to best support their metabolism and gut health."

Between 2018 and 2020, 1,4 million EU citizens signed the petition 'End the Cage Age', with the aim of ending cage housing for farm animals in Europe. In response to this citizens initiative, the European Parliament requested a study by Utrecht University researchers on the possibilities to end cage housing. On 13 April, the scientists will present their report 'End the Cage Age - Looking for Alternatives' to the European Parliament.

In the report, behavioural biologists, animal scientists, veterinarians and ethicists from Utrecht University's Faculty of Veterinary Medicine analysed the available scientific literature on alternatives to cage housing. "Our focus was on laying hens and pigs" says Bas Rodenburg, Professor of Animal Welfare at Utrecht University. "Because these are the species that are kept in the largest numbers, and cage-free alternatives are already available or in development for them." For other species - such as dairy and veal calves and rabbits - the researchers give a brief overview of the current situation and possibilities.

Foraging, rooting and pecking

"Our report shows that ending cage housing has positive effects on the behaviour and welfare of animals," Rodenburg says. "This is because animals in cage-free alternatives can exhibit their natural behaviour. Chickens and pigs are omnivores; they are normally foraging, rooting and pecking all day long. This behaviour is essential for these animals, but they need materials to rummage around in, such as sand, straw or wood shavings. That is difficult or impossible to achieve in cages."

Regarding sustainability, no large differences in environmental, social and economic impact between cage housing and cage-free alternatives were found in studies published to date. However, the alternatives do pose new risks. For example a higher risk of infectious diseases and social unrest, like feather pecking. To successfully switch to cage-free alternatives, farmers must therefore be trained and learn to work with the new systems.

For some species, like mink or geese and ducks for the production of foie gras, there is no cage-free alternative. The proposed alternative would therefore be a ban on production and a European import ban.

So ending the cage age is possible - but how?

The study shows that the switch to cage-free alternatives is possible. But how can this actually be achieved? "It has to be made attractive for farmers to make the switch," answers Rodenburg. "The required investments must result in added value for their products. And consumers must be prepared to pay a little more for this, so awareness is also needed among this group."

In the short term, this calls for financial measures such as subsidies for new welfare-friendly systems and welfare labels on products, enabling consumers to shop more consciously. In the longer term, legislation could prohibit certain types of cage housing. Rodenburg: "One of our most important recommendations is to involve all stakeholders in the process, so they can design the new and improved livestock farming together."

Presentation to the European Parliament

On Tuesday 13 April at 13:45 CET, two researchers from Utrecht University will present the report 'End the Cage Age - Looking for Alternatives' to the European Parliament: Bas Rodenburg, professor of Animal Welfare at Utrecht University, and Maite van Gerwen, project manager of the Centre for Sustainable Animal Stewardship at Utrecht University.

The presentation will be streamed live and can be followed by everyone (and watched later) via https://www.europarl.europa.eu/committees/en/peti/meetings/webstreaming.

The petition itself will be debated in parliament on 15 April.

Download the report (PDF): https://www.europarl.europa.eu/thinktank/en/document.html?reference=IPOL_STU(2020)658539

Why is sugar not transparent? Because light that penetrates a piece of sugar is scattered, altered and deflected in a highly complicated way. However, as a research team from TU Wien (Vienna) and Utrecht University (Netherlands) has now been able to show, there is a class of very special light waves for which this does not apply: for any specific disordered medium--such as the sugar cube you may just have put in your coffee--tailor-made light beams can be constructed that are practically not changed by this medium, but only attenuated. The light beam penetrates the medium, and a light pattern arrives on the other side that has the same shape as if the medium were not there at all.

This idea of "scattering-invariant modes of light" can also be used to specifically examine the interior of objects. The results have now been published in the journal Nature Photonics.

Astronomically many possible wave forms

The waves on a turbulent water surface can take on an infinite number of different shapes--and in a similar way, light waves can also be made in countless different forms. "Each of these light wave patterns is changed and deflected in a very specific way when you send it through a disordered medium," explains Prof. Stefan Rotter from the Institute of Theoretical Physics at TU Wien.

Together with his team, Stefan Rotter is developing mathematical methods to describe such light scattering effects. The expertise to produce and characterise such complex light fields was contributed by the team around Prof. Allard Mosk at Utrecht University. "As a light-scattering medium, we used a layer of zinc oxide--an opaque, white powder of completely randomly arranged nanoparticles," explains Allard Mosk, the head of the experimental research group.

First, you have to characterise this layer precisely. You shine very specific light signals through the zinc oxide powder and measure how they arrive at the detector behind it. From this, you can then conclude how any other wave is changed by this medium--in particular, you can calculate specifically which wave pattern is changed by this zinc oxide layer exactly as if wave scattering was entirely absent in this layer.

"As we were able to show, there is a very special class of light waves--the so-called scattering-invariant light modes, which produce exactly the same wave pattern at the detector, regardless of whether the light wave was only sent through air or whether it had to penetrate the complicated zinc oxide layer," says Stefan Rotter. "In the experiment, we see that the zinc oxide actually does not change the shape of these light waves at all--they just get a little weaker overall," explains Allard Mosk.

A stellar constellation at the light detector

As special and rare as these scattering-invariant light modes may be, with the theoretically unlimited number of possible light waves, one can still find many of them. And if you combine several of these scattering-invariant light modes in the right way, you get a scattering-invariant waveform again.

"In this way, at least within certain limits, you are quite free to choose which image you want to send through the object without interference," says Jeroen Bosch, who worked on the experiment as a Ph.D. student. "For the experiment we chose a constellation as an example: The Big Dipper. And indeed, it was possible to determine a scattering-invariant wave that sends an image of the Big Dipper to the detector, regardless of whether the light wave is scattered by the zinc oxide layer or not. To the detector, the light beam looks almost the same in both cases."

A look inside the cell

This method of finding light patterns that penetrate an object largely undisturbed could also be used for imaging procedures. "In hospitals, X-rays are used to look inside the body--they have a shorter wavelength and can therefore penetrate our skin. But the way a light wave penetrates an object depends not only on the wavelength, but also on the waveform," says Matthias Kühmayer, who works as a Ph.D. student on computer simulations of wave propagation. "If you want to focus light inside an object at certain points, then our method opens up completely new possibilities. We were able to show that using our approach the light distribution inside the zinc oxide layer can also be specifically controlled." This could be interesting for biological experiments, for example, where you want to introduce light at very specific points in order to look deep inside cells.

What the joint publication of the scientists from the Netherlands and Austria shows already is how important international cooperation between theory and experiment is for achieving progress in this area of research.

Squirrels and other tree-dwelling rodents evolved to have bigger brains than their burrowing cousins, a study suggests.

This greater brain power has given them key abilities needed to thrive in woodland habitats, including better vision and motor skills, and improved head and eye movements, researchers say.

Scientists have shed light on how the brains of rodents - a diverse group that accounts for more than 40 per cent of all mammals - have changed since they evolved around 50 million years ago.

Few studies looking into factors affecting brain size in mammals have taken account of extinct species. Previous research was also not able to reveal changes to the size of key parts of the brain.

Researchers from the University of Edinburgh used CT scans of skulls from 38 living and extinct rodent species to examine how the animals' brains have changed over time. The data shows that rodents' body mass, lifestyle and evolutionary history have affected the overall size of their brains and specific regions within it.

The relative brain size of tree squirrels has increased over time, driven largely by a sharp fall in their body mass, the team says.

Two key regions of the brain - including the neocortex, which is involved in vision and motor skills - also became larger in species living in trees. The petrosal lobules - which help with stabilising eye movements as the head rotates and tracks moving objects - also increased in size. Enlargement of these regions has helped tree-dwelling rodents adapt to life in complex environments, the team says.

By contrast, these parts of the brain are smaller in squirrels' closest living relatives - mountain beavers, which live in burrows - and some extinct rodent species that had a similar lifestyle. This is likely because burrowing rodents spend most of their time underground with little light, meaning good vision might be less crucial for them, than those in trees.

The research, published in the journal Communications Biology, was supported by a Marie Sk?odowska-Curie Actions Fellowship, European Research Council, National Agency for Research and Development, Leverhulme Trust and Natural Sciences and Engineering Research Council of Canada. The study also involved a researcher from the University of Toronto, Canada.

Dr Ornella Bertrand, of the University of Edinburgh's School of GeoSciences, who led the study, said: "Squirrels' ancestors were at an important juncture 34 million years ago. They were smaller than their closest extinct relatives, and there were far fewer primates living in trees than today, which opened up a new niche for them. When trees became available to them, squirrels' ancestors seized the opportunity. This transition was a key evolutionary step for squirrels as it enabled them to acquire larger and more complex brains."

A new 160-million-year-old arboreal pterosaur species, dubbed 'Monkeydactyl', has the oldest true opposed thumb - a novel structure previously not known in pterosaurs.

An international team of researchers from China, Brazil, UK, Denmark and Japan have described a new Jurassic pterosaur Kunpengopterus antipollicatus, which was discovered in the Tiaojishan Formation of Liaoning, China.

It is a small-bodied darwinopteran pterosaur, with an estimated wingspan of 85 cm. Most importantly, the specimen was preserved with an opposed pollex ("thumb") on both hands.

The species name 'antipollicatus' means 'opposite thumbed' in ancient Greek, in light of the opposed thumb of the new species. This is the first discovery of a pterosaur with an opposed thumb. It also represents the earliest record of a true opposed thumb in Earth's history. The researchers published their discovery today in the journal Current Biology.

A true opposed pollex is mostly present in mammals (e.g. primates) and some tree frogs, but extremely rare among extant reptiles except for chameleons. This discovery adds to the list that darwinopteran pterosaurs such as K. antipollicatus also evolved an opposed thumb.

The research team scanned the fossil of K. antipollicatus using micro-computed tomography (micro-CT), a technique making use of X-ray to image an object. By studying its forelimb morphology and musculature, they suggest that K. antipollicatus could have used its hand for grasping, which is likely an adaptation for arboreal life.

In order to test the arboreal interpretation, the team analysed K. antipollicatus and other pterosaurs using a set of anatomical characters related to arboreal adaptation. The results support K. antipollicatus as an arboreal species, but not the other pterosaurs from the same ecosystem. This suggests niche-partitioning among these pterosaurs and provides the first quantitative evidence that at least some darwinopteran pterosaurs were arboreal.

Fion Waisum Ma, co-author of the study and PhD researcher at the University of Birmingham, said: "The fingers of 'Monkeydactyl' are tiny and partly embedded in the slab. Thanks to micro-CT scanning, we could see through the rocks, create digital models and tell how the opposed thumb articulates with the other finger bones.

"This is an interesting discovery. It provides the earliest evidence of a true opposed thumb, and it is from a pterosaur - which wasn't known for having an opposed thumb."

Xuanyu Zhou from China University of Geosciences who led the study commented: "Tiaojishan palaeoforest is home to many organisms, including three genera of darwinopteran pterosaurs. Our results show that K. antipollicatus has occupied a different niche from Darwinopterus and Wukongopterus, which has likely minimized competition among these pterosaurs."

Rodrigo V. Pêgas from Federal University of ABC, in Sao Bernardo, Brazil, said: "Darwinopterans are a group of pterosaurs from the Jurassic of China and Europe, named after Darwin due to their unique transitional anatomy that has revealed how evolution affected the anatomy of pterosaurs throughout time.

"On top of that, a particular darwinopteran fossil has been preserved with two associated eggs, revealing clues to pterosaur reproduction. They've always been considered precious fossils for these reasons and it is impressive that new darwinopteran species continue to surprise us!"

Singapore, 12 April 2021 - Researchers from the Low Energy Electronic Systems (LEES) Interdisciplinary Research Group (IRG) at Singapore-MIT Alliance for Research and Technology (SMART), MIT's research enterprise in Singapore, together with Massachusetts Institute of Technology (MIT) and National University of Singapore (NUS) have found a method to quantify the distribution of compositional fluctuations in the indium gallium nitride (InGaN) quantum wells (QWs) at different indium concentrations.

InGaN light emitting diodes (LEDs) have revolutionised the field of solid-state lighting due to their high efficiencies and durability, and low costs. The colour of the LED emission can be changed by varying the indium concentration in the InGaN compound, giving InGaN LEDs the potential to cover the entire visible spectrum. InGaN LEDs with relatively low indium amounts compared to gallium, such as the blue, green, and cyan LEDs, have enjoyed significant commercial success for communication, industry and automotive applications. However, LEDs with higher indium concentrations, such as the red and amber LEDs, suffer from a drop in efficiency with the increasing amount of indium.

Currently, red and amber LEDs are made using the aluminium indium gallium phosphide (AlInGaP) material instead of InGaN due to InGaN's poor performance in the red and amber spectrum caused by the efficiency drop. Understanding and overcoming the efficiency drop is the first step towards developing InGaN LEDs covering the whole visible spectrum that would significantly reduce production costs.

In a paper titled "Unlocking the origin of compositional fluctuations in InGaN light emitting diodes", recently published in the prestigious journal Physical Review Materials, the team employed a multifaceted method to understand the origin of compositional fluctuations and their potential effect on the efficiency of InGaN LEDs. The accurate determination of compositional fluctuations is critical to understanding their role in reducing efficiency in InGaN LEDs with higher indium compositions.

"The [origin of the] efficiency drop experienced in higher indium concentration InGaN LEDs is still unknown to this date," says co-author of the paper, Professor Silvija Gradecak from the Department of Materials Science and Engineering at NUS and Principal Investigator at SMART LEES. "It is important to understand this efficiency drop to create solutions that will be able to overcome it. In order to do so, we have designed a method that is able to detect and study the compositional fluctuations in the InGaN QWs to determine its role in the efficiency drop."

The researchers developed a multifaceted method to detect indium compositional fluctuations in the InGaN QWs using synergistic investigation that combines complementary computational methods, advanced atomic-scale characterization and autonomous algorithms for image processing.

Tara Mishra, lead author of the paper and SMART PhD Fellow said, "This method developed and used in our research is of general applicability and can be adapted to other materials science investigations where compositional fluctuations need to be investigated."

"The method that we developed can be widely applied and provide significant value and impact on other materials science studies, where atomistic compositional fluctuations play an important role in material performance," said Dr Pieremanuele Canepa, co-author of the paper and Principal Investigator at SMART LEES and also Assistant Professor from the Department of Materials Science and Engineering, and Department of Chemical and Biomolecular Engineering at NUS. "The understanding of the atomic distribution of InGaN at varying indium concentrations is key to developing next-generation full-colour displays using the InGaN LED platform."

The research found that the indium atoms are randomly distributed in a relatively low indium content InGaN. On the other hand, partial phase separation is observed in higher indium content InGaN, where random compositional fluctuations are concurrent with pockets of indium-rich regions.

The findings advanced the understanding of the atomic microstructure of the InGaN and its potential effect on the performance of LEDs, paving the way for future research to determine the role of compositional fluctuations in the new generation of InGaN LEDs and design strategies to prevent the degradation of these devices.

Origami may sound more like art than science, but a complex folding pathway that proteins use to determine their shape has been harnessed by molecular biologists, enabling them to build some of the most complex synthetic protein nanostructures to date.

Using EMBL Hamburg's world-class beamline P12 at DESY's PETRA III synchrotron, a team of Slovenian researchers, in collaboration with EMBL's Svergun group, directed powerful X-ray beams at artificial proteins called coiled-coil origami. The proteins were designed to fold into a particular shape based on short modules that interact in pairs. By determining their molecular structure at the EMBL beamline, the researchers confirmed that the proteins folded into the desired shape and then studied the self-assembly process step by step. These findings advance understanding of how synthetic origami-like protein folding could potentially convey therapeutics, making it possible to more precisely target medication, minimising side-effects and maximising effectiveness.

"Recently scientists realised that natural proteins represent only a tiny fraction of possible protein shapes and that we can use design principles distinct from natural proteins. We can tailor designed proteins to make new materials, deliver drugs and vaccines, and much more," says Roman Jerala, a synthetic biologist at the National Institute of Chemistry in Ljubljana, Slovenia, who led the work to design and build a bipyramid (a diamond shape made of two conjoined triangular pyramids) from different types of artificial protein chains.

While scientists first attempted origami using DNA, proteins lend themselves more to potential applications. Proteins are the molecular machines of life, containing long chains of amino acids that fold into shapes specific to the functions they serve. That can mean bolstering immunity, talking to other cells, or carrying out other tasks to keep the body healthy. The proteins used in this study were folded into braided ropes called coiled coils, which readily bind to other parts of the same chain or to other molecules. This makes them a particularly good building material for creating custom-made nanostructures.

Roman's team first succeeded in this quest with a simpler origami structure - a single pyramid with a triangular base. They checked one chain of protein built of amino acids in a specific order and saw how it self-assembles. Then it was time to transform it from one structure to another, as if an origami lotus could transform into a crane. They put together two different chains of amino acids carrying a signal for a scissor enzyme called a protease, informing it where to make a cut in the origami protein. By doing so, they managed to force the protein to perform its origami transformation into a different shape.

Shining a light on protein solutions

To do this kind of work, the researchers need high-tech tools. EMBL Hamburg's beamline P12 is particularly suited for this purpose, and EMBL's Svergun group is world-renowned for its expertise in a technique called small-angle X-ray scattering (SAXS). Since 2018, EMBL scientists have been collaborating with the group from Slovenia, supporting them in using SAXS to study the structure of origami proteins.

"In SAXS, we shine X-rays at a glass capillary that contains the protein solutions. As the X-rays scatter as they pass through the solution, we have a way to interpret the structures," says group leader Dmitri Svergun. "Here, most data collection work is automated, and we also provide important software and analysis support in collaborations like this one."

Using the EMBL beamline, together with electron microscopy, calorimetry, computational modelling, and other methods, the researchers assembled the data needed to identify the structures of the origami proteins and confirm that the shapes would fit into their overall origami design.

"It's our job to obtain the best signal from the beamline and create the optimal conditions for getting data," says Stefano Da Vela, a postdoc in the Svergun group. "We provide tools to help make sense of the SAXS experimental data and create 3D models from the data."

The researchers observed that their synthetic proteins assemble 'bottom up', which means that small, detailed bits form first and then assemble together into a bigger structure. Understanding this will help researchers construct more complex protein origami structures with more precision. "SAXS analysis was crucial in identifying which design leads to the desired shapes, and the superb tools developed at EMBL allowed us to detect unique features of our designed cages," says Fabio Lapenta, a postdoc at the National Institute of Chemistry and the lead author of their recent paper in Nature Communications that described this work. "Coiled coils are excellent tools that can be used in cells as well as in isolated proteins. We think we can expand the potential of coiled-coil protein origami to design many new protein folds and introduce interesting functionalities."

Smoking cannabis when you're young may increase your risk of developing heart disease later, according to a recent University of Guelph study.

In the first study to look at specific risk indicators for cardiovascular disease (CVD) in young, healthy cannabis users, researchers found subtle but potentially important changes in heart and artery function.

Cigarette smoking is known to affect cardiovascular health, causing changes to blood vessels and the heart. Less is known about the impact of smoking cannabis on long-term CVD risk, even as use of the substance grows in Canada and abroad. Cannabis is the most commonly used recreational substance worldwide after alcohol.

"Cannabis is really widely used as a recreational substance all around the world and is becoming increasingly so," said Christian Cheung, a PhD student in the Human Performance and Health Research Lab, part of the Department of Human Health and Nutritional Sciences (HHNS). "Scientists haven't done that research with cannabis."

Cheung is the lead author of the study, published recently in the Journal of Applied Physiology. His co-authors were Dr. Jamie Burr and Dr. Philip Millar, both professors in HHNS and PhD student Alexandra Coates.

The team studied 35 subjects aged 19 to 30, half of whom were cannabis users. For all subjects, they used ultrasound imaging to look at the heart and arteries. They measured arterial stiffness and arterial function, or the ability of arteries to appropriately expand with greater blood flow. All three measures are indicators of cardiovascular function and potential disease risk.

Arterial stiffness was greater in cannabis users than in non-users. The team measured how fast a pressure wave travelled down the artery; stiffer arteries transmit a wave more quickly.

In cannabis users, cardiac function - inferred from how the heart moves as seen in echocardiographic images -- was lower than in non-users.

Cheung said the team was surprised to see no difference in artery dilation in response to changing blood flow.

All three measures normally change in cigarette smokers, with stiffer arteries and lower vascular and heart function.

"We don't yet know why in cannabis users there's no difference in vascular function," he said.

Cheung said differences may reflect variations in how tobacco and cannabis are consumed, as well as amounts and frequency and the user's age.

"We looked at young cannabis users. In the cigarette literature, heavy, long-term smokers show reduced vascular function but that's not necessarily the case for younger smokers."

The U of G researchers plan further studies to learn about potential impacts of these changes and disease risk in people who use cannabis.

"This is exciting new data, suggesting that even before more overt signs and symptoms of cardiovascular disease are present, there may be more subtle indications in altered physiological function," said Burr.

"It also paves the way to our next studies, aimed at understanding the direct effects of cannabis consumption, and how this may interact with common stressors of everyday life, like exercise."

Cheung emphasized that few studies have been done on the impacts of cannabis use on cardiovascular health.

"This is an exciting field of research given the ubiquity of cannabis use and the knowledge gap that exists, it's a field ripe with opportunity."